Binding foot or binding attachment? If the latter, here's a recent discussion
Has anyone used a binding attachment?
I have tried the latter and didn't like it for quilt binding. I'm not sure a binding foot would open large enough to feed a quilt sandwich. In either case, both fold the binding twice towards the center, so the thickness of the binding where it wraps around the quilt edge is only 1 layer of fabric (vs. traditional quilt binding which is double fabric thickness). Both create a binding that's folded like seam binding rather than quilt binding.